target/arm/gdbstub64.c - third_party/qemu - Git at Google

 /*
  * ARM gdb server stub: AArch64 specific functions.
  *
  * Copyright (c) 2013 SUSE LINUX Products GmbH
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  */
 #include "qemu/osdep.h"
 #include "qemu/log.h"
 #include "cpu.h"
 #include "internals.h"
 #include "gdbstub/helpers.h"

 int aarch64_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     ARMCPU *cpu = ARM_CPU(cs);
     CPUARMState *env = &cpu->env;

     if (n < 31) {
         /* Core integer register.  */
         return gdb_get_reg64(mem_buf, env->xregs[n]);
     }
     switch (n) {
     case 31:
         return gdb_get_reg64(mem_buf, env->xregs[31]);
     case 32:
         return gdb_get_reg64(mem_buf, env->pc);
     case 33:
         return gdb_get_reg32(mem_buf, pstate_read(env));
     }
     /* Unknown register.  */
     return 0;
 }

 int aarch64_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n)
 {
     ARMCPU *cpu = ARM_CPU(cs);
     CPUARMState *env = &cpu->env;
     uint64_t tmp;

     tmp = ldq_p(mem_buf);

     if (n < 31) {
         /* Core integer register.  */
         env->xregs[n] = tmp;
         return 8;
     }
     switch (n) {
     case 31:
         env->xregs[31] = tmp;
         return 8;
     case 32:
         env->pc = tmp;
         return 8;
     case 33:
         /* CPSR */
         pstate_write(env, tmp);
         return 4;
     }
     /* Unknown register.  */
     return 0;
 }

 int aarch64_gdb_get_fpu_reg(CPUState *cs, GByteArray *buf, int reg)
 {
     ARMCPU *cpu = ARM_CPU(cs);
     CPUARMState *env = &cpu->env;

     switch (reg) {
     case 0 ... 31:
     {
         /* 128 bit FP register - quads are in LE order */
         uint64_t *q = aa64_vfp_qreg(env, reg);
         return gdb_get_reg128(buf, q[1], q[0]);
     }
     case 32:
         /* FPSR */
         return gdb_get_reg32(buf, vfp_get_fpsr(env));
     case 33:
         /* FPCR */
         return gdb_get_reg32(buf, vfp_get_fpcr(env));
     default:
         return 0;
     }
 }

 int aarch64_gdb_set_fpu_reg(CPUState *cs, uint8_t *buf, int reg)
 {
     ARMCPU *cpu = ARM_CPU(cs);
     CPUARMState *env = &cpu->env;

     switch (reg) {
     case 0 ... 31:
         /* 128 bit FP register */
         {
             uint64_t *q = aa64_vfp_qreg(env, reg);
             q[0] = ldq_le_p(buf);
             q[1] = ldq_le_p(buf + 8);
             return 16;
         }
     case 32:
         /* FPSR */
         vfp_set_fpsr(env, ldl_p(buf));
         return 4;
     case 33:
         /* FPCR */
         vfp_set_fpcr(env, ldl_p(buf));
         return 4;
     default:
         return 0;
     }
 }

 int aarch64_gdb_get_sve_reg(CPUState *cs, GByteArray *buf, int reg)
 {
     ARMCPU *cpu = ARM_CPU(cs);
     CPUARMState *env = &cpu->env;

     switch (reg) {
     /* The first 32 registers are the zregs */
     case 0 ... 31:
     {
         int vq, len = 0;
         for (vq = 0; vq < cpu->sve_max_vq; vq++) {
             len += gdb_get_reg128(buf,
                                   env->vfp.zregs[reg].d[vq * 2 + 1],
                                   env->vfp.zregs[reg].d[vq * 2]);
         }
         return len;
     }
     case 32:
         return gdb_get_reg32(buf, vfp_get_fpsr(env));
     case 33:
         return gdb_get_reg32(buf, vfp_get_fpcr(env));
     /* then 16 predicates and the ffr */
     case 34 ... 50:
     {
         int preg = reg - 34;
         int vq, len = 0;
         for (vq = 0; vq < cpu->sve_max_vq; vq = vq + 4) {
             len += gdb_get_reg64(buf, env->vfp.pregs[preg].p[vq / 4]);
         }
         return len;
     }
     case 51:
     {
         /*
          * We report in Vector Granules (VG) which is 64bit in a Z reg
          * while the ZCR works in Vector Quads (VQ) which is 128bit chunks.
          */
         int vq = sve_vqm1_for_el(env, arm_current_el(env)) + 1;
         return gdb_get_reg64(buf, vq * 2);
     }
     default:
         /* gdbstub asked for something out our range */
         qemu_log_mask(LOG_UNIMP, "%s: out of range register %d", __func__, reg);
         break;
     }

     return 0;
 }

 int aarch64_gdb_set_sve_reg(CPUState *cs, uint8_t *buf, int reg)
 {
     ARMCPU *cpu = ARM_CPU(cs);
     CPUARMState *env = &cpu->env;

     /* The first 32 registers are the zregs */
     switch (reg) {
     /* The first 32 registers are the zregs */
     case 0 ... 31:
     {
         int vq, len = 0;
         uint64_t *p = (uint64_t *) buf;
         for (vq = 0; vq < cpu->sve_max_vq; vq++) {
             env->vfp.zregs[reg].d[vq * 2 + 1] = *p++;
             env->vfp.zregs[reg].d[vq * 2] = *p++;
             len += 16;
         }
         return len;
     }
     case 32:
         vfp_set_fpsr(env, *(uint32_t *)buf);
         return 4;
     case 33:
         vfp_set_fpcr(env, *(uint32_t *)buf);
         return 4;
     case 34 ... 50:
     {
         int preg = reg - 34;
         int vq, len = 0;
         uint64_t *p = (uint64_t *) buf;
         for (vq = 0; vq < cpu->sve_max_vq; vq = vq + 4) {
             env->vfp.pregs[preg].p[vq / 4] = *p++;
             len += 8;
         }
         return len;
     }
     case 51:
         /* cannot set vg via gdbstub */
         return 0;
     default:
         /* gdbstub asked for something out our range */
         break;
     }

     return 0;
 }

 int aarch64_gdb_get_pauth_reg(CPUState *cs, GByteArray *buf, int reg)
 {
     ARMCPU *cpu = ARM_CPU(cs);
     CPUARMState *env = &cpu->env;

     switch (reg) {
     case 0: /* pauth_dmask */
     case 1: /* pauth_cmask */
     case 2: /* pauth_dmask_high */
     case 3: /* pauth_cmask_high */
         /*
          * Note that older versions of this feature only contained
          * pauth_{d,c}mask, for use with Linux user processes, and
          * thus exclusively in the low half of the address space.
          *
          * To support system mode, and to debug kernels, two new regs
          * were added to cover the high half of the address space.
          * For the purpose of pauth_ptr_mask, we can use any well-formed
          * address within the address space half -- here, 0 and -1.
          */
         {
             bool is_data = !(reg & 1);
             bool is_high = reg & 2;
             ARMMMUIdx mmu_idx = arm_stage1_mmu_idx(env);
             ARMVAParameters param;

             param = aa64_va_parameters(env, -is_high, mmu_idx, is_data, false);
             return gdb_get_reg64(buf, pauth_ptr_mask(param));
         }
     default:
         return 0;
     }
 }

 int aarch64_gdb_set_pauth_reg(CPUState *cs, uint8_t *buf, int reg)
 {
     /* All pseudo registers are read-only. */
     return 0;
 }

 static void output_vector_union_type(GDBFeatureBuilder *builder, int reg_width,
                                      const char *name)
 {
     struct TypeSize {
         const char *gdb_type;
         short size;
         char sz, suffix;
     };

     static const struct TypeSize vec_lanes[] = {
         /* quads */
         { "uint128", 128, 'q', 'u' },
         { "int128", 128, 'q', 's' },
         /* 64 bit */
         { "ieee_double", 64, 'd', 'f' },
         { "uint64", 64, 'd', 'u' },
         { "int64", 64, 'd', 's' },
         /* 32 bit */
         { "ieee_single", 32, 's', 'f' },
         { "uint32", 32, 's', 'u' },
         { "int32", 32, 's', 's' },
         /* 16 bit */
         { "ieee_half", 16, 'h', 'f' },
         { "uint16", 16, 'h', 'u' },
         { "int16", 16, 'h', 's' },
         /* bytes */
         { "uint8", 8, 'b', 'u' },
         { "int8", 8, 'b', 's' },
     };

     static const char suf[] = { 'b', 'h', 's', 'd', 'q' };
     int i, j;

     /* First define types and totals in a whole VL */
     for (i = 0; i < ARRAY_SIZE(vec_lanes); i++) {
         gdb_feature_builder_append_tag(
             builder, "<vector id=\"%s%c%c\" type=\"%s\" count=\"%d\"/>",
             name, vec_lanes[i].sz, vec_lanes[i].suffix,
             vec_lanes[i].gdb_type, reg_width / vec_lanes[i].size);
     }

     /*
      * Now define a union for each size group containing unsigned and
      * signed and potentially float versions of each size from 128 to
      * 8 bits.
      */
     for (i = 0; i < ARRAY_SIZE(suf); i++) {
         int bits = 8 << i;

         gdb_feature_builder_append_tag(builder, "<union id=\"%sn%c\">",
                                        name, suf[i]);
         for (j = 0; j < ARRAY_SIZE(vec_lanes); j++) {
             if (vec_lanes[j].size == bits) {
                 gdb_feature_builder_append_tag(
                     builder, "<field name=\"%c\" type=\"%s%c%c\"/>",
                     vec_lanes[j].suffix, name,
                     vec_lanes[j].sz, vec_lanes[j].suffix);
             }
         }
         gdb_feature_builder_append_tag(builder, "</union>");
     }

     /* And now the final union of unions */
     gdb_feature_builder_append_tag(builder, "<union id=\"%s\">", name);
     for (i = ARRAY_SIZE(suf) - 1; i >= 0; i--) {
         gdb_feature_builder_append_tag(builder,
                                        "<field name=\"%c\" type=\"%sn%c\"/>",
                                        suf[i], name, suf[i]);
     }
     gdb_feature_builder_append_tag(builder, "</union>");
 }

 GDBFeature *arm_gen_dynamic_svereg_feature(CPUState *cs, int base_reg)
 {
     ARMCPU *cpu = ARM_CPU(cs);
     int reg_width = cpu->sve_max_vq * 128;
     int pred_width = cpu->sve_max_vq * 16;
     GDBFeatureBuilder builder;
     char *name;
     int reg = 0;
     int i;

     gdb_feature_builder_init(&builder, &cpu->dyn_svereg_feature.desc,
                              "org.gnu.gdb.aarch64.sve", "sve-registers.xml",
                              base_reg);

     /* Create the vector union type. */
     output_vector_union_type(&builder, reg_width, "svev");

     /* Create the predicate vector type. */
     gdb_feature_builder_append_tag(
         &builder, "<vector id=\"svep\" type=\"uint8\" count=\"%d\"/>",
         pred_width / 8);

     /* Define the vector registers. */
     for (i = 0; i < 32; i++) {
         name = g_strdup_printf("z%d", i);
         gdb_feature_builder_append_reg(&builder, name, reg_width, reg++,
                                        "svev", NULL);
     }

     /* fpscr & status registers */
     gdb_feature_builder_append_reg(&builder, "fpsr", 32, reg++,
                                    "int", "float");
     gdb_feature_builder_append_reg(&builder, "fpcr", 32, reg++,
                                    "int", "float");

     /* Define the predicate registers. */
     for (i = 0; i < 16; i++) {
         name = g_strdup_printf("p%d", i);
         gdb_feature_builder_append_reg(&builder, name, pred_width, reg++,
                                        "svep", NULL);
     }
     gdb_feature_builder_append_reg(&builder, "ffr", pred_width, reg++,
                                    "svep", "vector");

     /* Define the vector length pseudo-register. */
     gdb_feature_builder_append_reg(&builder, "vg", 64, reg++, "int", NULL);

     gdb_feature_builder_end(&builder);

     return &cpu->dyn_svereg_feature.desc;
 }
	/*
	* ARM gdb server stub: AArch64 specific functions.
	*
	* Copyright (c) 2013 SUSE LINUX Products GmbH
	*
	* This library is free software; you can redistribute it and/or
	* modify it under the terms of the GNU Lesser General Public
	* License as published by the Free Software Foundation; either
	* version 2.1 of the License, or (at your option) any later version.
	*
	* This library is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* Lesser General Public License for more details.
	*
	* You should have received a copy of the GNU Lesser General Public
	* License along with this library; if not, see <http://www.gnu.org/licenses/>.
	*/
	#include "qemu/osdep.h"
	#include "qemu/log.h"
	#include "cpu.h"
	#include "internals.h"
	#include "gdbstub/helpers.h"

	int aarch64_cpu_gdb_read_register(CPUState cs, GByteArray mem_buf, int n)
	{
	ARMCPU *cpu = ARM_CPU(cs);
	CPUARMState *env = &cpu->env;

	if (n < 31) {
	/* Core integer register. */
	return gdb_get_reg64(mem_buf, env->xregs[n]);
	}
	switch (n) {
	case 31:
	return gdb_get_reg64(mem_buf, env->xregs[31]);
	case 32:
	return gdb_get_reg64(mem_buf, env->pc);
	case 33:
	return gdb_get_reg32(mem_buf, pstate_read(env));
	}
	/* Unknown register. */
	return 0;
	}

	int aarch64_cpu_gdb_write_register(CPUState cs, uint8_t mem_buf, int n)
	{
	ARMCPU *cpu = ARM_CPU(cs);
	CPUARMState *env = &cpu->env;
	uint64_t tmp;

	tmp = ldq_p(mem_buf);

	if (n < 31) {
	/* Core integer register. */
	env->xregs[n] = tmp;
	return 8;
	}
	switch (n) {
	case 31:
	env->xregs[31] = tmp;
	return 8;
	case 32:
	env->pc = tmp;
	return 8;
	case 33:
	/* CPSR */
	pstate_write(env, tmp);
	return 4;
	}
	/* Unknown register. */
	return 0;
	}

	int aarch64_gdb_get_fpu_reg(CPUState cs, GByteArray buf, int reg)
	{
	ARMCPU *cpu = ARM_CPU(cs);
	CPUARMState *env = &cpu->env;

	switch (reg) {
	case 0 ... 31:
	{
	/* 128 bit FP register - quads are in LE order */
	uint64_t *q = aa64_vfp_qreg(env, reg);
	return gdb_get_reg128(buf, q[1], q[0]);
	}
	case 32:
	/* FPSR */
	return gdb_get_reg32(buf, vfp_get_fpsr(env));
	case 33:
	/* FPCR */
	return gdb_get_reg32(buf, vfp_get_fpcr(env));
	default:
	return 0;
	}
	}

	int aarch64_gdb_set_fpu_reg(CPUState cs, uint8_t buf, int reg)
	{
	ARMCPU *cpu = ARM_CPU(cs);
	CPUARMState *env = &cpu->env;

	switch (reg) {
	case 0 ... 31:
	/* 128 bit FP register */
	{
	uint64_t *q = aa64_vfp_qreg(env, reg);
	q[0] = ldq_le_p(buf);
	q[1] = ldq_le_p(buf + 8);
	return 16;
	}
	case 32:
	/* FPSR */
	vfp_set_fpsr(env, ldl_p(buf));
	return 4;
	case 33:
	/* FPCR */
	vfp_set_fpcr(env, ldl_p(buf));
	return 4;
	default:
	return 0;
	}
	}

	int aarch64_gdb_get_sve_reg(CPUState cs, GByteArray buf, int reg)
	{
	ARMCPU *cpu = ARM_CPU(cs);
	CPUARMState *env = &cpu->env;

	switch (reg) {
	/* The first 32 registers are the zregs */
	case 0 ... 31:
	{
	int vq, len = 0;
	for (vq = 0; vq < cpu->sve_max_vq; vq++) {
	len += gdb_get_reg128(buf,
	env->vfp.zregs[reg].d[vq * 2 + 1],
	env->vfp.zregs[reg].d[vq * 2]);
	}
	return len;
	}
	case 32:
	return gdb_get_reg32(buf, vfp_get_fpsr(env));
	case 33:
	return gdb_get_reg32(buf, vfp_get_fpcr(env));
	/* then 16 predicates and the ffr */
	case 34 ... 50:
	{
	int preg = reg - 34;
	int vq, len = 0;
	for (vq = 0; vq < cpu->sve_max_vq; vq = vq + 4) {
	len += gdb_get_reg64(buf, env->vfp.pregs[preg].p[vq / 4]);
	}
	return len;
	}
	case 51:
	{
	/*
	* We report in Vector Granules (VG) which is 64bit in a Z reg
	* while the ZCR works in Vector Quads (VQ) which is 128bit chunks.
	*/
	int vq = sve_vqm1_for_el(env, arm_current_el(env)) + 1;
	return gdb_get_reg64(buf, vq * 2);
	}
	default:
	/* gdbstub asked for something out our range */
	qemu_log_mask(LOG_UNIMP, "%s: out of range register %d", __func__, reg);
	break;
	}

	return 0;
	}

	int aarch64_gdb_set_sve_reg(CPUState cs, uint8_t buf, int reg)
	{
	ARMCPU *cpu = ARM_CPU(cs);
	CPUARMState *env = &cpu->env;

	/* The first 32 registers are the zregs */
	switch (reg) {
	/* The first 32 registers are the zregs */
	case 0 ... 31:
	{
	int vq, len = 0;
	uint64_t p = (uint64_t ) buf;
	for (vq = 0; vq < cpu->sve_max_vq; vq++) {
	env->vfp.zregs[reg].d[vq * 2 + 1] = *p++;
	env->vfp.zregs[reg].d[vq * 2] = *p++;
	len += 16;
	}
	return len;
	}
	case 32:
	vfp_set_fpsr(env, (uint32_t )buf);
	return 4;
	case 33:
	vfp_set_fpcr(env, (uint32_t )buf);
	return 4;
	case 34 ... 50:
	{
	int preg = reg - 34;
	int vq, len = 0;
	uint64_t p = (uint64_t ) buf;
	for (vq = 0; vq < cpu->sve_max_vq; vq = vq + 4) {
	env->vfp.pregs[preg].p[vq / 4] = *p++;
	len += 8;
	}
	return len;
	}
	case 51:
	/* cannot set vg via gdbstub */
	return 0;
	default:
	/* gdbstub asked for something out our range */
	break;
	}

	return 0;
	}

	int aarch64_gdb_get_pauth_reg(CPUState cs, GByteArray buf, int reg)
	{
	ARMCPU *cpu = ARM_CPU(cs);
	CPUARMState *env = &cpu->env;

	switch (reg) {
	case 0: /* pauth_dmask */
	case 1: /* pauth_cmask */
	case 2: /* pauth_dmask_high */
	case 3: /* pauth_cmask_high */
	/*
	* Note that older versions of this feature only contained
	* pauth_{d,c}mask, for use with Linux user processes, and
	* thus exclusively in the low half of the address space.
	*
	* To support system mode, and to debug kernels, two new regs
	* were added to cover the high half of the address space.
	* For the purpose of pauth_ptr_mask, we can use any well-formed
	* address within the address space half -- here, 0 and -1.
	*/
	{
	bool is_data = !(reg & 1);
	bool is_high = reg & 2;
	ARMMMUIdx mmu_idx = arm_stage1_mmu_idx(env);
	ARMVAParameters param;

	param = aa64_va_parameters(env, -is_high, mmu_idx, is_data, false);
	return gdb_get_reg64(buf, pauth_ptr_mask(param));
	}
	default:
	return 0;
	}
	}

	int aarch64_gdb_set_pauth_reg(CPUState cs, uint8_t buf, int reg)
	{
	/* All pseudo registers are read-only. */
	return 0;
	}

	static void output_vector_union_type(GDBFeatureBuilder *builder, int reg_width,
	const char *name)
	{
	struct TypeSize {
	const char *gdb_type;
	short size;
	char sz, suffix;
	};

	static const struct TypeSize vec_lanes[] = {
	/* quads */
	{ "uint128", 128, 'q', 'u' },
	{ "int128", 128, 'q', 's' },
	/* 64 bit */
	{ "ieee_double", 64, 'd', 'f' },
	{ "uint64", 64, 'd', 'u' },
	{ "int64", 64, 'd', 's' },
	/* 32 bit */
	{ "ieee_single", 32, 's', 'f' },
	{ "uint32", 32, 's', 'u' },
	{ "int32", 32, 's', 's' },
	/* 16 bit */
	{ "ieee_half", 16, 'h', 'f' },
	{ "uint16", 16, 'h', 'u' },
	{ "int16", 16, 'h', 's' },
	/* bytes */
	{ "uint8", 8, 'b', 'u' },
	{ "int8", 8, 'b', 's' },
	};

	static const char suf[] = { 'b', 'h', 's', 'd', 'q' };
	int i, j;

	/* First define types and totals in a whole VL */
	for (i = 0; i < ARRAY_SIZE(vec_lanes); i++) {
	gdb_feature_builder_append_tag(
	builder, "<vector id=\"%s%c%c\" type=\"%s\" count=\"%d\"/>",
	name, vec_lanes[i].sz, vec_lanes[i].suffix,
	vec_lanes[i].gdb_type, reg_width / vec_lanes[i].size);
	}

	/*
	* Now define a union for each size group containing unsigned and
	* signed and potentially float versions of each size from 128 to
	* 8 bits.
	*/
	for (i = 0; i < ARRAY_SIZE(suf); i++) {
	int bits = 8 << i;

	gdb_feature_builder_append_tag(builder, "<union id=\"%sn%c\">",
	name, suf[i]);
	for (j = 0; j < ARRAY_SIZE(vec_lanes); j++) {
	if (vec_lanes[j].size == bits) {
	gdb_feature_builder_append_tag(
	builder, "<field name=\"%c\" type=\"%s%c%c\"/>",
	vec_lanes[j].suffix, name,
	vec_lanes[j].sz, vec_lanes[j].suffix);
	}
	}
	gdb_feature_builder_append_tag(builder, "</union>");
	}

	/* And now the final union of unions */
	gdb_feature_builder_append_tag(builder, "<union id=\"%s\">", name);
	for (i = ARRAY_SIZE(suf) - 1; i >= 0; i--) {
	gdb_feature_builder_append_tag(builder,
	"<field name=\"%c\" type=\"%sn%c\"/>",
	suf[i], name, suf[i]);
	}
	gdb_feature_builder_append_tag(builder, "</union>");
	}

	GDBFeature arm_gen_dynamic_svereg_feature(CPUState cs, int base_reg)
	{
	ARMCPU *cpu = ARM_CPU(cs);
	int reg_width = cpu->sve_max_vq * 128;
	int pred_width = cpu->sve_max_vq * 16;
	GDBFeatureBuilder builder;
	char *name;
	int reg = 0;
	int i;

	gdb_feature_builder_init(&builder, &cpu->dyn_svereg_feature.desc,
	"org.gnu.gdb.aarch64.sve", "sve-registers.xml",
	base_reg);

	/* Create the vector union type. */
	output_vector_union_type(&builder, reg_width, "svev");

	/* Create the predicate vector type. */
	gdb_feature_builder_append_tag(
	&builder, "<vector id=\"svep\" type=\"uint8\" count=\"%d\"/>",
	pred_width / 8);

	/* Define the vector registers. */
	for (i = 0; i < 32; i++) {
	name = g_strdup_printf("z%d", i);
	gdb_feature_builder_append_reg(&builder, name, reg_width, reg++,
	"svev", NULL);
	}

	/* fpscr & status registers */
	gdb_feature_builder_append_reg(&builder, "fpsr", 32, reg++,
	"int", "float");
	gdb_feature_builder_append_reg(&builder, "fpcr", 32, reg++,
	"int", "float");

	/* Define the predicate registers. */
	for (i = 0; i < 16; i++) {
	name = g_strdup_printf("p%d", i);
	gdb_feature_builder_append_reg(&builder, name, pred_width, reg++,
	"svep", NULL);
	}
	gdb_feature_builder_append_reg(&builder, "ffr", pred_width, reg++,
	"svep", "vector");

	/* Define the vector length pseudo-register. */
	gdb_feature_builder_append_reg(&builder, "vg", 64, reg++, "int", NULL);

	gdb_feature_builder_end(&builder);

	return &cpu->dyn_svereg_feature.desc;
	}